The angular momentum catastrophe prompted comparisons of the \(j\)  of simulated haloes
to that of observed galaxies. In these studies, the \(j\)  of
dark matter haloes is measured out to the virial radius, \(R_{Vir}\) , which is standardly defined as \(R_{\Delta =200}\) ,
and is the effective radius at which the dark matter ceases to collapse into the halo.
[1]} and [2]} found that observed galaxies have 45% and 70% of the \(j\)  of their expected
host haloes in simulations, respectively, under the assumptions that galaxies can be related to
simulated host haloes via characteristic rotation velocities directly and via a scaling factor, respectively.
Recently, [3]} found that the spin parameters of observed galaxies are \(\sim 60\) % of those of simulated haloes. These studies are consistent once differences in assumptions and approximations are accounted for.
